1. Technical Field
The present invention relates to a fabrication method for an organic EL device.
2. Related Art
An organic electroluminescence (EL) device has a structure where a light-emitting layer made of a light-emitting material is interposed between an anode (pixel electrode) and a cathode (counter electrode). For example, as described in JP-A-2007-188653, a resonance structure is known where a reflection film is provided on the side of the anode opposite to the side facing the light-emitting layer to allow light emitted from the light-emitting layer to travel between the reflection film and the cathode thereby extracting light having a spectrum high in peak intensity and narrow in width. Having such a structure, the color reproducibility of light emission can be improved.
An example of a fabrication method for an organic EL device is as follows: an anode is formed on a reflection film, and a transparent conductive film is formed on the anode for varying the light path length according to the colors such as RGB. A light-emitting layer and a cathode are then formed sequentially on the transparent conductive film. The device can therefore be configured to have an optimal light path length for each color, and this can enhance the brightness and improve the color reproducibility.
To attain an optimal light path length, however, it is necessary to form the multilayer film including the transparent conductive film, etc. to have a thickness corresponding to a desired wavelength of each color in each light-emitting region, and this causes formation of a step along the periphery of a pixel region of each color, etc. When a step is formed along the periphery of the pixel region, unintentional parasitic light emission may occur due to a deviation of the value of an optimal light path length (resonance), causing emission of a different color in a step portion. To avoid this problem, it is necessary to form a light-shielding oxide film covering the step portion to prevent parasitic light emission. This will complicate the fabrication process, and also reduce the light emission-capable region for each color because of the light-shielding film formed along the periphery of the pixel region of each color.